1. Field of the Invention
The field of the invention is in low-cost knockdown shelf systems in which trays formed of low-cost paperboard or fiberboard material are supported by tubular posts and by support members underlying the trays.
2. Description of the Prior Art
My prior patent, Hepp, U.S. Pat. No. 4,428,487, shows a sectional display in which angular corner posts engage grooved portions on the underside of plastic trays. In order to achieve alignment at the four corners in a vertical assembly of three to five shelves of the rack, a plurality of rib portions are provided to assure engagement and locking of the corners. The construction is very sturdy but does not meet the need of a low-cost rack which is used mainly for storing rather than for display but which still is capable of supporting heavy loads and does not require the use of relatively expensive molded plastic, wood, or metal for the construction of the trays or shelves.
Paper trays are known for use in shelf storage and handling systems, for example, a paperboard tray constructed of a single blank used in handling and sorting mail, is shown in Pfaffendorf, et al, U.S. Pat. No. 3,784,083. However, such paperboard trays have not been herefore used in an assembly in the type in my prior U.S. Pat. No. 4,428,487.
Nawman, et al, U.S. Pat. No. 3,172,542 shows a tray having a paper bottom which is reinforced by a cross brace.
Wentzel, U.S. Pat. No. 3,490,702, describes a disposable paper tray in which the bottom panel is made of paperboard and is reinforced by cross braces.